The Involvement of Cysteine Proteases and Protease Inhibitor Genes in the Regulation of Programmed Cell Death in Plants (original) (raw)
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Reactive oxygen species and their role in plant defence and cell wall metabolism
Planta, 2012
Harnessing the toxic properties of reactive oxygen species (ROS) to Wght oV invading pathogens can be considered a major evolutionary success story. All aerobic organisms have evolved the ability to regulate the levels of these toxic intermediates, whereas some have evolved elaborate signalling pathways to dramatically increase the levels of ROS and use them as weapons in mounting a defence response, a process commonly referred to as the oxidative burst. The balance between steady state levels of ROS and the exponential increase in these levels during the oxidative burst has begun to shed light on complex signalling networks mediated by these molecules. Here, we discuss the diVerent sources of ROS that are present in plant cells and review their role in the oxidative burst. We further describe two well-studied ROS generating systems, the NADPH oxidase and apoplastic peroxidase proteins, and their role as the primary producers of ROS during pathogen invasion. We then discuss what is known about the metabolic and proteomic Xuxes that occur in plant cells during the oxidative burst and after pathogen recognition, and try to highlight underlying biochemical processes that may provide more insight on the complex regulation of ROS in plants.
This article is introductory to the series of works presented in this special issue on the homeostasis and the signaling roles of reactive oxygen species (ROS) in plants. Upper half of this article briefly describes the history of the ROS study in the field of plant immunity research initiated by the observation that the attacks by pathogenic microorganisms possibly stimulate the burst of ROS production in the plant tissues. The topics covered in the series of works presented here include the plants' responses to abiotic oxidative stress (atmospheric ozone), regulation of seed germination , chemical interaction between parasitic and host plants and the draught tolerance, all controlled through homeostasis of ROS at biochemical and molecular biological levels. Lastly a discussion forum was proposed to further deepen our understanding of ROS behaviors in plants.
Australian Journal of Crop Science
Reactive oxygen species (ROS) are a by-product of normal cell metabolism in plants; however, under stress conditions, the balance between production and elimination is disturbed. ROS rapidly inactivate enzymes, damage vital cellular organelles in plants, and destroy membranes by inducing the degradation of pigments, proteins, lipids and nucleic acids which ultimately results in cell death. In addition to degrading macromolecules, ROS act as a diffusible signal in signal transduction pathways and also as a secondary messenger in various developmental pathways in plants. Plants possess a complex battery of enzymatic and non-enzymatic antioxidative defense systems that can protect cells from oxidative damage and scavenge harmful ROS that are produced in excess of those normally required for various metabolic reactions. The mechanism by which ROS is generated in aerobic organisms is poorly understood. This review paper describes the generation, origin, and role of ROS in signal transduction and cell death, and the removal of ROS by antioxidative defense systems in plants during various developmental pathways.
The antioxidant systems vis-à -vis reactive oxygen species during plant–pathogen interaction
Plant Physiology and Biochemistry, 2003
Plant resistance to pathogens requires the activation of complex metabolic pathways in the infected cells, aimed at recognizing pathogen presence and hindering its propagation within plant tissues. In spite of this both compatible and incompatible responses induce alterations in plant metabolism, only in the latter the plant is able to efficiently block pathogen penetration without suffering excessive damage. One of the most studied incompatible responses is based on the hypersensitive response (HR), in which cells surrounding the site of pathogen penetration switch on genes encoding for phytoalexin synthesis and other pathogenesis related proteins before activating programmed cell death (PCD). The production of reactive oxygen species (ROS) is a key event in HR. Several enzymatic systems have been proposed to be responsible for the oxidative burst characterizing HR. In this review, the involvement of antioxidant redox systems, in particular those related to ascorbate (ASC) and glutathione (GSH), in activating both compatible and incompatible plant responses is analysed. Increasing lines of evidence indicate that alterations in the levels and/or redox state of ASC and/or GSH, as well as in the activity of their redox enzymes, occur during the HR programme. These alterations do not seem to be a mere consequence of the oxidative stress induced by the massive ROS production, but they are induced as part of the transduction pathways triggering defence responses and PCD. The possibility that ASC and GSH systems are links in a redox signalling chain activating defence strategies is also discussed.
Reactive oxygen species in plants: their generation, signal transduction, and scavenging mechanisms
2011
Reactive oxygen species (ROS) are a by-product of normal cell metabolism in plants; however, under stress conditions, the balance between production and elimination is disturbed. ROS rapidly inactivate enzymes, damage vital cellular organelles in plants, and destroy membranes by inducing the degradation of pigments, proteins, lipids and nucleic acids which ultimately results in cell death. In addition to degrading macromolecules, ROS act as a diffusible signal in signal transduction pathways and also as a secondary messenger in various developmental pathways in plants. Plants possess a complex battery of enzymatic and non-enzymatic antioxidative defense systems that can protect cells from oxidative damage and scavenge harmful ROS that are produced in excess of those normally required for various metabolic reactions. The mechanism by which ROS is generated in aerobic organisms is poorly understood. This review paper describes the generation, origin, and role of ROS in signal transduction and cell death, and the removal of ROS by antioxidative defense systems in plants during various developmental pathways.
Molecular Plant-Microbe Interactions, 2009
Chemiluminescence detection of reactive oxygen species (ROS) triggered in tobacco BY-2 cells by the fungal elicitor cryptogein was previously demonstrated to be abolished in cells transformed with an antisense construct of the plasma membrane NADPH oxidase, NtrbohD. Here, using electron microscopy, it has been confirmed that the first hydrogen peroxide production occurring a few minutes after challenge of tobacco cells with cryptogein is plasma membrane located and NtrbohD mediated. Furthermore, the presence of NtrbohD in detergent-resistant membrane fractions could be associated with the presence of NtrbohD-mediated hydrogen peroxide patches along the plasma membrane. Comparison of the subcellular localization of ROS in wild-type tobacco and in plants transformed with antisense constructs of NtrbohD revealed that this enzyme is also responsible for the hydrogen peroxide production occurring at the plasma membrane after infiltration of tobacco leaves with cryptogein. Finally, the reactivity of wild-type and transformed plants to the elicitor and their resistance against the pathogenic oomycete Phytophthora parasitica were examined. NtrbohD-mediated hydrogen peroxide production does not seem determinant for either hypersensitive response development or the establishment of acquired resistance but it is most likely involved in the signaling pathways associated with the protection of the plant cell. Plants are exposed to a large number of microorganisms, although only a relatively small proportion of them are able to cause diseases. Prevention of penetration by pathogens during plant infection is generally dependent on an accurate time course of the pathogen perception by host cells and activation of a signaling cascade triggering a network of coordinated responses. The rapid production of reactive oxygen species (ROS), called the oxidative burst, is one of the earliest events detected during incompatible interactions between plants and pathogens. The generation of ROS has been considered for a long time to contribute to several disease resistance strategies (antimicrobial activity, cross-linking of cell wall proteins, induction of defense related genes, and so on) (